1. Field of the Invention
The present invention relates generally to graphics systems, and more particularly to a system and method for generating different appearances of an object from a plurality of appearances made available to a graphics system.
2. Related Art
Graphics systems are often used to generate images representing objects. An object of an image may have an appearance. For example, an image may include the face of a person with different expressions such as smiling, laughing, frowning, etc.
An object, as used in the present application, may be any entity which is the subject of a representation in an image. For example, an ocean may be the subject of a representation. A snapshot image (e.g., a photograph) of an ocean is an appearance with the associated tidal waves, colors, lighting etc.
A user may wish to generate images representing different appearances of an object using a graphics system. As a practical matter, a graphics system may store (or be provided) only a limited number of images with a corresponding number of appearances. A user may desire to generate additional images with new appearances which are not already provided to the graphics system.
What is therefore needed is a system and method which allows a user to generate new appearances of images stored in a graphics system.
The present invention is directed to a system and method for generating different new appearances of an object using a plurality of appearances provided to the system. Attribute data sets corresponding to the plurality of appearances are stored in an embodiment of the present invention. The attribute data values in each set define an expression of the object. A user may then selectively specify one or more of the plurality of appearances and assign a weight to each of the appearances.
A new or different appearance is generated by combining the attribute data in the specified appearances according to the assigned weights. For example, if a user assigns a weight of 0.25 to a first appearance and 0.75 to a second appearance, all attributes in the first appearance may contribute 25% and the attributes of the second appearance may contribute 75% to the final new appearance generated in accordance with the present invention. The remaining appearances may be viewed as being assigned a weight equal to zero, i.e., these appearances do not contribute to the new appearance generated. According to a further feature of the invention, a user may interactively change the weights corresponding to any of the appearances to generate new appearances with desired attributes.
The data corresponding to different appearances may be stored in one of several ways. In one embodiment, an attribute data set corresponding to a reference appearance is stored. The attribute data sets for the remaining appearances are defined relative to the corresponding attributes in the reference attribute set. In an alternative embodiment, each of the attribute data values are defined as absolute values. In either embodiment, a user is provided the option to assign interactively the weights of the respective appearances, and a new appearance is generated by combining the stored attribute data sets according to the specified weights.
In one application, the present invention can be implemented to generate a plurality of new facial expressions. In this application, attribute data sets representing predetermined expressions (e.g., happy, grumpy, angry etc.) of a face are stored. A user may then generate new or different facial expressions by combining the stored expressions according to weights assigned by the user. For example, a user may combine an angry expression and a happy expression according to desired weights (proportions) to generate a new expression.
In another application, the present invention is applied to lighting or luminosity, wherein different light sources impact the appearance of an area being rendered. An area may include, for example, a surface, a room, a building, terrains, an entity, any graphical object or combination of graphical object and surfaces. In this application, a designer stores attribute data indicating how the area looks in the presence of light from individual light sources. The look of an area may change depending on several factors such as distance to the area, brightness level of the light source, and the surface normal vector of the object being illuminated. A user may then combine the individual light sources according to desired weights associated with each light source to generate new looks of the area.
Thus, an advantage of the invention is that it enables a user to generate new appearances. This is accomplished by providing a set of pre-defined appearances, and allowing the user to combine these appearances to generate new appearances.
Another advantage of the invention is that the user may generate new appearances in which the pre-defined appearances contribute to a desired degree to the new appearance generated. The user specifies a weight corresponding to each pre-defined appearance to control the degree of contribution of each pre-defined appearance.
The present invention may be applied in several real-world applications. For example, new expressions of a face may be generated by providing some pre-defined defined expressions to a system implemented in accordance with the present invention. Similarly, the impact of several light sources in different brightness levels on the look of an area may be assessed by using the present invention.
According to a further feature of the invention, new appearances can be generated by morphing a texture attribute and/or a surface normal vector attribute.
Further features and advantages of the invention, as well as the structure and operation of various embodiments of the invention, are described in detail below with reference to the accompanying drawings.